A great place to start is your BMI. Check the link I have provided. At 5'-6" your weight should be around 150. As a note, I am male, with muscular build, my BMI shows I need to be 175. At 185 I am fairly trim, so 175 feels very light to me. the BMI can be used as a starting point. However, if your BMI is approaching 30, then you need to address where you are at. Good luck!